In the production of 3D movies, disparity is the horizontal separation of the corresponding pixels of the left-eye view and the right-eye view of an object. The amount and polarity of disparity determines the depth of the object in the 3D plane, which causes the object to appear either close or far away relative to the normal image plane. If the disparity is negative, i.e., if the right-eye image is to the left of the left-eye image, then the disparate object appears closer than the normal image plane. If the disparity is positive, i.e., if the right-eye image is to the right of the left-eye image, then the disparate object appears farther away or behind the normal image plane. Too much disparity can cause headaches or even make viewers ill. Too little disparity can reduce the 3D effect. Disparity measurements are necessary for 3D video production and can be used in camera setup, production, post-production, quality assurance, etc. Measurements in video post-production are becoming more important as computer generated graphics are combined with live material where determining the disparity is critical to merge these two technologies together.
Disparity is conventionally measured using various approaches. In one approach, a user enlarges the picture and measures the object differences with a ruler. While this approach is simple, it is also crude and prone to inaccuracies. A more elegant approach is to use a video waveform monitor. In this approach, the user manually moves a sample cursor for a first measurement, manually moves the sample cursor for a second measurement, calculates the difference between the two measurements, and then divides the result by the video format width in pixels to obtain the disparity in pixels relative to the video horizontal resolution width. This approach is more accurate, however it is time consuming, and it requires that the user have explicit details of the video format.
What is desired is a quicker and easier way to make disparity measurements.